High TMR in MXene-Based Mn ₂ CF ₂ /Ti ₂ CO ₂ /Mn ₂ CF ₂ Magnetic Tunneling Junction

We suggest an MXene-based magnetic tunnel junction (MTJ) design. The device characteristics of the MTJ were investigated by nonequilibrium Green's function formalism within the density functional theory. Inspired by the first synthesized magnetic MAX crystal of Mn ₂ GaC, its two-dimensional (2D) counterpart of the half-metallic Mn ₂ CF ₂ MXene layer was selected as the magnetic electrode. The tunneling barrier was chosen as Ti ₂ CO ₂ MXene, which is one of the most studied MXenes in experimental and theoretical works. It is beneficial that both the electrodes and the tunneling barrier are 2D materials from the same material family and have similar structures. The common device problem of lattice mismatch does not occur in our MTJ design because the lattice parameters are compatible. In addition, the band gap of Ti ₂ CO ₂ tunneling barrier is almost the same as the half-metallic gap of Mn ₂ CF ₂ electrodes. Both the barrier and the electrodes have a common C layer that contributes the most to the transmission. Our MTJ design consists of structurally and electronically well-matched components. We find that the tunneling magnetoresistance ratio has a peak value of ≈10 ⁶ and stays higher than ≈10 ³ under the bias voltages up to 1 V. Since the applied bias voltages are within the energy gap of the tunneling barrier, the half-metallic character of the conduction is preserved up to 1 V. The tunneling-based transmission was observed in all of the three devices with varying tunneling barrier widths, and the current decreases with increasing width. The MXene-based MTJ has promising device characteristics.